Grid Fitting
Rendering characters or glyphs for display and printing is problematic, particularly if the characters are complex. This is particularly true for Chinese, Japanese, and Korean (CJK) character sets, see FIG. 1A. The characters shown are represented by outlines as described in the TrueType Reference Manual, Apple Computer, Inc. It is an object of the invention to automatically align the outlines to a sampling grid (e.g., a pixel or sub-pixel grid) for the purpose of rendering, see the related Applications.
Hints
Hints are a set of rules or procedures stored with each glyph to specify how the glyph should be modified during rendering to preserve features such as symmetry, stroke weight, and a uniform appearance across all the glyphs in a typeface. Hinting requires aligning edges of characters to the sampling grid. At small screen sizes, with or without antialiasing, hinting is critical for producing clear and legible text for human readers. Hinting can be manual, automatic, or combinations thereof.
Manual hinting is labor intensive and expensive. For example, developing a well-hinted typeface for a Japanese or Chinese font, which can have more than ten thousand glyphs, can take years. Because the focus of hinting is on improving the rendering quality of body type, the hints tend to be ineffective for type placed along arbitrary paths and for animated type.
Current methods for automatic hinting produce reasonable results for simple scripts such as Latin, but are inadequate for complex scripts such as Chinese and Japanese. Consequently, there is a need for an automatic hinting method that can effectively handle complex glyphs. With automatic hinting, labor cost is eliminated and font size is significantly reduced because manual hints, which are stored in a font file, are no longer needed.